Changes in lung tissue associated with severe asthma in horses are also present in milder cases, researchers in Canada report.
Researchers in the University of Montreal study said remodeling of the central airways in horses with severe asthma is known to occur, but, until now, it was not known whether a similar process occurred in horses with mild or moderate asthma.
Amandine Bessonna and her fellow researchers set about evaluating lung lesions in 12 horses with mild or moderate asthma, with another eight horses employed as controls.
The study team examined the history of the horses, including a complete blood count, serum biochemistry, and the results of analysis of bronchoalveolar lavage fluid samples (fluid flushed in and out of the lungs).
Lung tissue biopsies, held in a tissue bank, were also examined microscopically.
Their results, reported in the Journal of Veterinary Internal Medicine, revealed alterations of the central airway in horses with mild or moderate asthma as compared to the non-asthmatic control horses. The researchers found tissue remodeling of the bronchial lamina propria, epithelium, and smooth muscle was present in the asthma-affected horses in the study.
They said thickening of the lamina propria has been linked to lung resistance in severe asthma.
“These findings indicate this thickening of the lamina propria might also contribute to the airway obstruction in horses with mild or moderate asthma.”
They said bronchial smooth muscle fibrosis was significantly increased in the asthma-affected horses in the study, when compared to the control horses. In horses with severe asthma, smooth muscle fibrosis is increased in peripheral and central airways.
The study team comprised Bessonnat, Pierre Hélie, Carolyn Grimes, and Jean-Pierre Lavoie, all with the University of Montreal.
Airway remodeling in horses with mild and moderate asthma
Amandine Bessonnat, Pierre Hélie, Carolyn Grimes, Jean-Pierre Lavoie
Journal of Veterinary Internal Medicine, December 8, 2021, https://doi.org/10.1111/jvim.16333